The usual methods of drug administration are the oral ingestion of tablets, capsules, liquid drug formulations etc., parenteral administration into the blood stream or tissues, and rectal suppository administration. Such methods are far from ideal, since they provide wide variations in plasma concentration of drugs at different times between dosages, ranging from ineffectively low concentrations to toxic levels at which harmful side effects can be experienced. Moreover, such methods are essentially non-site specific, and deliver the drug to substantially all parts of the body and all body organs, not just the area needing treatment by the drug. Accordingly, such methods are wasteful in terms of amounts of drugs used, and also possibly harmful in subjecting body parts and organs to foreign substances having no need for treatment by them.
A particular form of drug therapy where localized action of the drug is important is cancer therapy. Drugs which are effective in attacking malignant cells to limit their proliferation have a tendency to attack benign cells also, so that it is highly desirable to limit the location of their action to that of the malignancy, and to ensure that effective but not excessive amounts of such drugs are used, at any particular time. Previous attempts to administer such drugs by direct injection into the location or organ having the malignancy are only partially effective, because of leakage of the drug from this location. Such leakage cannot be totally prevented, with the result that excessive quantities need to be administered.
It is an object of the present invention to provide novel drug delivery systems.
It is a further object to provide novel compositions of pharmaceuticals which can be delivered to specific treatment sites in a body, and released thereto in a controlled manner.